Boolean Trouble
Difficulty: Intermediate
Objective: Learn what a boolean is and why to use it. Also learn how to fix boolean's that aren't working.
The 3D Printing Ninja
3DNinjaneer@gmail.com
Objective: Learn what a boolean is and why to use it. Also learn how to fix boolean's that aren't working.
What is a boolean?
A boolean is just a funny word that is a way to combine things. In blender the boolean modifier is used to combine 2 objects. When using the modifier the choices are: Union - combines the two objects into one, Difference - subtracts one item from the other, and intersect - only where both objects are. The pictures below illustrate:How to use a Boolean?
- Select the first object (Note that which object you choose first does make a difference)
- Add a Boolean Modifier
- Choose the second object (Note that which object you choose second does make a difference)
- Choose what type of Boolean Operation (If you don't suceed at first, try all of the operations, as sometimes the "wrong" one accomplishes what you want)
- Delete the old object, (If you do not, it will create a non-manifold that won't print)
Why is my boolean not working?
Non-manifold trouble
If either of your objects are non-manifolds, then the boolean will most likely not work. To learn more about non-manifolds see this post: http://3dprintingninja.blogspot.com/2014/07/non-manifolds-your-worst-nightmare.html
Many programs may create a new object when a boolean is created. Therefore make sure that there is only one object, and delete any items that should not be there. The first image below shows two objects before boolean. This would cause printing problems. The second is after a boolean modifier, this would print.
Normals
Using the properties window [N], you can visualize the normals, which basically means which way the face is facing. You will probably need to change the size of the normal in order to see them. Inspect the faces to make sure all normals are properly facing outwards.
Should a normal be the wrong direction you can flip the normal by selecting the face and then in the tool window, select Normal-->flip direction. If multiple normals are in the wrong direction you can select the whole shape and choose Normal-->Recalculate.
Non-mesh Object
Make sure that the objects that you are combining are meshes. Things such as curves and text are not mesh until they are converted. Convert the text [Alt]+[C] and then use a boolean modifier.
Improper Positioning
This is a silly problem, but emphasizes the importance of changing views as you model. A boolean modifier will not work if the objects are not touching. See the image below as it may appear touching on the left, but changing views we can see the two are not touching.Please leave your comments.
and as always thanks for visiting,The 3D Printing Ninja
3DNinjaneer@gmail.com
Category: Basics, Blender, boolean, Non-manifolds, Trouble Shooting
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